Many sensing applications require the use of liquid flow sensors. Flow sensors, for example, can be utilized for measure flow rates in a variety of commercial, industrial and medical applications. Various medical, process, and industrial applications, ranging from portable ventilators supplying anesthetizing agents to large-scale processing plants in a chemical plant require the use of flow sensors. In such applications, flow control is an inherent aspect of proper operation, which can be achieved in part by utilizing flow sensors to measure the flow rate of fluid within a flow system. In medical applications, for example, it is often required to accurately measure the flow rates of fluids introduced intravenously to medical patients and thereby control the flow rate of such fluids.
In many flow systems, e.g., fuel gas flow systems containing a binary mixture of methanol and water, the chemical composition of the fluid may change frequently. Also, a particular flow system may be required to flow more than one fluid having different chemical and thermo-physical properties. For example, in a semiconductor processing system that passes an N2 gas, the N2 gas may at times be replaced by H2 or helium gas, depending on the needs of the process; or in a natural gas metering system, the composition of the natural gas may change due to non-uniform concentration profiles of the gas. Thus, measuring the flow rates of fluids, including those of differing chemical compositions (e.g., differing in density, thermal conductivity, specific heat, etc.) requires precise and efficient flow sensor devices.
In many flow sensing applications, a need exists for disposable flow sensor devices. One advantage of disposable devices is that they can be manufactured inexpensively and in greater quantities. Such devices are well-suited for limited use applications. One of the problems with conventional flow sensor packages is the difficulty in configuring such devices for both limited use and in an inexpensive and efficient manner. It is believed that the flow sensor device disclosed herein overcomes the limitations of conventional flow sensor devices.